The present invention relates to an adjusting mechanism and an adjusting method of a valve-lift amount of an internal combustion engine for rocking a rocker arm when a camshaft is rotated and for rocking a rocking cam provided on the camshaft to open and close a valve.
To enhance engine performances, there is a known valve operating mechanism which variably controls a valve-lift amount corresponding to variation of an engine operating state as disclosed in Japanese Patent Applications Laid-open Nos. 2002-221014 and H11-107725. According to this valve operating mechanism, a rocking cam opens and closes a suction valve by a rotation force transmitted, through a rocker arm or a link member, from a drive cam which is an eccentric rotation cam provided on a camshaft. The valve operating mechanism controls rotation of a control cam on an outer periphery of a control shaft disposed in parallel to the camshaft and changes a rocking fulcrum of the rocker arm, thereby varying the valve-lift amount corresponding to the engine operating state.